I am more than happy with my P-Flow. Yes, it is quite loud (Sounds purposeful though).
I had a look into the specs for the different flow rates for the EVOMS vs P-Flow but could find nothing on the EVOMS. At the end of the day they are just unrestricted pipes with high flow filters on the end. I would have thought the performance difference between the two is minimal (there is probably more variation in 2 different tanks of petrol!)
As for looks; they look pretty much the same and nearly no-one sees it anyway! The EVOMS has the filter slightly tipped down (an expensive bend IMO).
In any case I find driving around with my bonnet up so people can see my CAI is very dangerous, as the view out of the windscreen is severely restricted and on the MK5 the wipers are disabled. Also leaving it open in car parks and on the drive is just asking to have bits stolen.
Oh, and I got a 4 day old P-Flow at 1/2 price because the seller didn't like the sound (no-brainer). It's not for sale.